242 research outputs found
Wavelet analysis applied to SAR images to detect atmospheric structures
The aim of this work is to evaluate the possibilities offered by the wavelet analysis in the study of the spatial structure of the radar backscatter, which is linked to the spatial structure of the marine atmospheric boundary layer. Continuous wavelet analysis has been applied to a SAR image of the sea surface, previously analysed by the more classical Conditional Sampling technique. The main problem
coped with has been to select, among the large number of wavelet maps produced by the analysis (256), those containing the more energetic backscatter structures. Since the phenomenon imaged by SAR was the convective turbulence, a multiscale and quasi-periodic or intermittent process, a selection of wavelet maps according to their mean energy was unsuccessful. On the contrary, a method based on the
calculation of the standard deviation of the less probable highest wavelet amplitudes led to a right selection of the wavelet maps and to a convincing reconstruction of the map of backscatter structures, which resulted similar to that provided through the Conditional Sampling
Towards the wind direction determination in RADARSAT-2 polarimetrie images
AbstractThe interpretation of SAR images of the sea surface is difficult, due to the complexity of the geophysics and of the interaction mechanisms between electromagnetic and sea waves. The determination of the wind direction is crucial for the evaluation of the wind speed, but its retrieval is still an open issue. One of the few methods able to extract the sea surface wind from SAR data only has been developed and extensively applied to Envisat ASAR images in the past years, using the two-dimensional wavelet transform to detect the backscatter signature related to locally coherent wind cells. A preliminary analysis on the applicability of this method to RADARSAT-2 fully polarimetric images has been conducted to verify if polarimetry may improve the detection of backscatter imprints related to the wind direction
Expression pattern analysis of odorant-binding proteins in the pea aphid Acyrthosiphon pisum
Odorant-binding proteins (OBPs) are soluble proteins mediating chemoreception in insects. In previous research, we investigated the molecular mechanisms adopted by aphids to detect the alarm pheromone (E)-\u3b2-farnesene and we found that the recognition of this and structurally related molecules is mediated by OBP3 and OBP7. Here, we show the differential expression patterns of 5 selected OBPs (OBP1, OBP3, OBP6, OBP7, OBP8) obtained performing quantitative RT-PCR and immunolocalization experiments in different body parts of adults and in the 5 developmental instars, including winged and unwinged morphs, of the pea aphid Acyrthosiphon pisum. The results provide an overall picture that allows us to speculate on the relationship between the differential expression of OBPs and their putative function. The expression of OBP3, OBP6, and OBP7 in the antennal sensilla suggests a chemosensory function for these proteins, whereas the constant expression level of OBP8 in all instars could suggest a conserved role. Moreover, OBP1 and OBP3 are also expressed in nonsensory organs. A light and scanning electron microscopy study of sensilla on different body parts of aphid, in particular antennae, legs, mouthparts, and cornicles-cauda, completes this research providing a guide to facilitate the mapping of OBP expression profiles
Efficacy and safety of colchicine for the treatment of myopericarditis
Objective Clinical trials have evaluated the efficacy and safety of colchicine only in simple pericarditis, excluding cases of concomitant myocarditis. The aim of this paper is to evaluate the efficacy and safety of colchicine for the treatment of the first attack of acute pericarditis with concomitant myocardial involvement. Methods Double-centre retrospective cohort study analysing consecutive patients admitted for first attack of pericarditis with myocarditis and treated with or without colchicine. The primary efficacy end point was the time to the first recurrence. Propensity score matching was used to generate two groups of patients with similar baseline characteristics. Colchicine-associated side effects were analysed as safety end-point. Results A total of 175 patients (mean age 46.2±20.1 years, 25.1% females, 88.6% with idiopathic/viral aetiology) were included. Seventy-nine (45.1%) patients were treated with colchicine. After a median follow-up of 25.3 (IQR 8.3-45.6) months, 58 (33.1%) patients had recurrences. The propensity score generated two groups of 73 patients with similar baseline characteristics but the use of colchicine. Patients treated with colchicine had a lower incidence of recurrences (respectively, 19.2% vs 43.8%; p=0.001) and a longer event-free survival (p=0.005). In multivariable analysis, women (HR 1.97, 95% CI 1.04 to 3.73; p=0.037) and corticosteroid use (HR 2.27, 95% CI 1.15 to 4.47; p=0.018) were independent risk factors for recurrences. Colchicine-associated side effects were mild and occurred in 3 (1.7%) patients. Conclusion In patients with first attack of pericarditis associated with myocardial involvement, colchicine was safe and efficacious for the reduction of recurrences
Light--like Wilson loops and gauge invariance of Yang--Mills theory in 1+1 dimensions
A light-like Wilson loop is computed in perturbation theory up to for pure Yang--Mills theory in 1+1 dimensions, using Feynman and
light--cone gauges to check its gauge invariance. After dimensional
regularization in intermediate steps, a finite gauge invariant result is
obtained, which however does not exhibit abelian exponentiation. Our result is
at variance with the common belief that pure Yang--Mills theory is free in 1+1
dimensions, apart perhaps from topological effects.Comment: 10 pages, plain TeX, DFPD 94/TH/
New Insight on the Bioactivity of Solanum aethiopicum Linn. Growing in Basilicata Region (Italy): Phytochemical Characterization, Liposomal Incorporation, and Antioxidant Effects
Food extract’s biological effect and its improvement using nanotechnologies is one of the challenges of the last and the future decades; for this reason, the antioxidant effect of scarlet eggplant extract liposomal incorporation was investigated. Scarlet eggplant (Solanum aethiopicum L.) is a member of the Solanaceae family, and it is one of the most consumed vegetables in tropical Africa and south of Italy. This study investigated the antioxidant activity and the phytochemical composition of S. aethiopicum grown in the Basilicata Region for the first time. The whole fruit, peel, and pulp were subjected to ethanolic exhaustive maceration extraction, and all extracts were investigated. The HPLC-DAD analysis revealed the presence of ten phenolic compounds, including hydroxycinnamic acids, flavanones, flavanols, and four carotenoids (one xanthophyll and three carotenes). The peel extract was the most promising, active, and the richest in specialized metabolites; hence, it was tested on HepG2 cell lines and incorporated into liposomes. The nanoincorporation enhanced the peel extract’s antioxidant activity, resulting in a reduction of the concentration used. Furthermore, the extract improved the expression of endogenous antioxidants, such as ABCG2, CAT, and NQO1, presumably through the Nrf2 pathway
Crystal structures and binding dynamics of Odorant-Binding Protein 3 from two aphid species Megoura viciae and Nasonovia ribisnigri
Aphids use chemical cues to locate hosts and find mates. The vetch aphid Megoura viciae feeds exclusively
on the Fabaceae, whereas the currant-lettuce aphid Nasonovia ribisnigri alternates hosts between the
Grossulariaceae and Asteraceae. Both species use alarm pheromones to warn of dangers. For N. ribisnigri this
pheromone is a single component (E)-β-farnesene but M. viciae uses a mixture of (E)-β-farnesene, (-)-α-
pinene, β-pinene, and limonene. Odorant-binding proteins (OBP) are believed to capture and transport such
semiochemicals to their receptors. Here, we report the first aphid OBP crystal structures and examine their
molecular interactions with the alarm pheromone components. Our study reveals some unique structural
features: 1) the lack of internal ligand binding site; 2) a striking groove in the surface of the proteins as a
putative binding site; 3) the N-terminus rather than the C-terminus occupies the site closing off the
conventional OBP pocket. The results from fluorescent binding assays, molecular docking and dynamics
demonstrate that OBP3 from M. viciae can bind to all four alarm pheromone components and the differential
ligand binding between these very similar OBP3s from the two aphid species is determined mainly by the
direct π-π interactions between ligands and the aromatic residues of OBP3s in the binding pocket
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